GenVibe - Community for Pontiac Vibe Enthusiasts

Just getting into car audio. I am not ready to change out the head unit but wanted better sound. I changed out all four factory speakers. This helped but I needed more base. I cut the wiring to the back speakers and installed a 10" subwoofer and a 500 watt amplifier. I used the high-level inputs on the amp. This amp has a RCA throughput so I connected a 200 watt amp using RCA wires to drive the rear speakers. Once everything was connected I turned on the HU but noticed a significant decrease in the subwoofer volume. When I disconnect the RCA cables from the second amp the sub really kicks in. I can't figure out what the problem could be.Can I split the speaker wire from the head unit and run them into each amp seperately? Should I get a line-level convertor to convert the high-level to RCA? I have a spare BOSS AVA-CR200 2 channel electronic crossover. Would you recommend using this? Any help is greatly appreciated.

Your install really confuses me, but you should run the line converter into your rear speaker amp. From that full range amp I would run my rcas to the sub amp and turn the amp to low pass.